Scientists have found living organisms trapped in crystals (晶体) that could be 50,000 years old.

    The organisms were found in a hot, but beautiful cave system in Naica, Mexico. These ancient life forms can be seen only with a microscope. Penelope Boston, who leads the Astrobiology Institute at NASA, the space agency of the United States, says the ancient microbes were able to live by eating minerals such as iron.

    She spoke about the discovery recently at a meeting of the American Association for the Advancement of Science. If the findings are confirmed, they will show how microbes can survive in extreme conditions. Forty different kinds of microbes and some viruses were found in the underground area. The genetic structures of these organisms are 10 percent different from those of their nearest relatives.

    The caves in Naica are 800 kilometers deep. They were once used for mining lead. Before the miners began working in the caves, the area was separated from the surface and the outside world. Some of the caves are as big as the large religious centers built during Europe's Middle Ages. There are crystals covering the walls. The caves are so hot that scientists must wear special clothing to keep cool. The clothing keeps the crystals safe from human germs (病菌) or other damage. Boston said the researchers could only work for about 20 minutes at a time before they had to go to a room that was 38 degrees Celsius to cool down.

    NASA officials would not let Boston share her findings with scientific experts before last week's announcement. So scientists could not say much about the findings. But Norine Noonan, a biologist with the University of South Florida, said she believed them. “Why are we surprised?”Noonan asked. “ As a biologist, I would say life on Earth is extremely tough and extremely colorful.”

    Boston is also studying microbes commonly found inside caves in other countries, such as Ukraine and the United States. These microbes appear to be impossible to kill. Boston said they show how difficult life on Earth can be.

    You may have heard of the American Dream, an ideal that has powered the hopes of Americans for generations.

    It began as a belief that the US was a land of opportunity, and that anyone could achieve success through hard work. The dream has referred to home ownership, a good job, retirement security or each generation doing better than the last for a long time.

    Yet today, this concept seems to have greatly changed. As Tune magazine pointed out, quite different from the older generation, many Millennials (the generation born after 1980) redefine the American Dream as “day-to-day control of your life”. They “prize job mobility, flexible schedules, any work that is more interesting than typing, and the ability to travel”, said the magazine.

    Home ownership, once the cornerstone of the American Dream, is becoming a smaller priority for this generation. Meanwhile, nearly 40% of them choose travel as part of their dream. And running their own business is a rising favorite, as nearly 26% of Millennials consider self-employment as part of their dream.

    So what has led to this huge change?

    Many point fingers at the poor economy. “Modern young Americans seem bound to face a world stamped by ever narrowing opportunity,” noted The Daily Beast.

    “The rate of 16-to-24-year-olds out of school and out of work is unusually high at 15%. Many college graduates have taken jobs that don't require a degree,” Time reported.

    The magazine worries that these difficulties may lead to a lost generation who are “unable to ever truly find their feet on the corporation's ladder”.

    Dan Kadlec, a reporter of Time, sees Millennials as resetting their expectations. “This situation is different for young adults today,” he wrote. “A true American dream has to feel attainable, and many Millennials are feeling they can only attain a day-to-day lifestyle that suits them.”

    Humans and many other mammals have unusually efficient internal temperature regulating systems that automatically maintain stable core body temperatures（核心体温）in cold winters and warm summers. In addition, people have developed cultural patterns and technologies that help them adjust to extremes of temperature and humidity（湿度）.

In very cold climates, there is a constant danger of developing hypothermia（低体温）, which is a life threatening drop in core body temperature to below normal levels. The normal temperature for humans is about 37.0℃. However, differences in persons and even the time of day can cause it to be as much as 6℃ higher or lower in healthy individuals. It is also normal for core body temperature to be lower in elderly people. Hypothermia begins to occur when the core body temperature drops to 34.4℃. Below 29.4℃, the body cools more rapidly because its natural temperature regulating system usually fails. The rapid decline in core body temperature is likely to result in death. However, there have been rare cases in which people have been saved after their temperatures had dropped to 13.9-15.6℃. This happened in 1999 to a Swedish woman who was trapped under an ice sheet in freezing water for 80 minutes. She was found unconscious, not breathing, and her heart had stopped beating, yet she was eventually saved despite the fact that her temperature had dropped to 13.7℃.

In extremely hot climates or as a result of uncontrollable infections, core body temperatures can rise to equally dangerous levels. This is hyperthermia. Life threatening hyperthermia typically starts in humans when their temperatures rise to 40.6-41.7℃. Only a few days at this extraordinarily high temperature level is likely to result in the worsening of internal organs and death.

    Black Friday is the day after Thanksgiving Day and the Friday before Cyber Monday in the United States. It is not a federal holiday, but is a public holiday in some states. Many people take a day of their annual leave on the day after Thanksgiving Day. Some people use this to make trips to see family members or friends who live in other areas or to go on vacation. Others use it to start shopping for the Christmas season. Many organizations also close for the Thanksgiving weekend.

    Shopping for Christmas presents is also popular on Black Friday. Many stores have special offers and lower their prices on some goods, such as toys. Public transit systems may run on their normal schedule or may have changes. Some stores extend their opening hours on Black Friday. There can also be congestion on roads to popular shopping destinations.

    Black Friday is one of the busiest shopping days in the USA. There are two popular theories as to why the day after Thanksgiving Day is called Black Friday. One theory is that the wheels of vehicles in heavy traffic on the day after Thanksgiving Day left many black markings on the road surface, leading to the term Black Friday. The other theory is that the term Black Friday comes from an old way of recording business accounts. Losses were recorded in red ink and profits in black ink. Many businesses, particularly small businesses, started making profits prior to Christmas. Many hoped to start showing a profit, marked in black ink, on the day after Thanksgiving Day.

    Have you ever heard someone say "You totally look like you're a Jessica" or something similar? People seem to think that they know what kind of person a "Jessica" or a "Michael" looks like. Why is this?

    According to a study published in the Journal of Personality and Social Psychology, humans tend to associate people's names with their appearances, and can even guess someone's name based on how they look.

    Researchers at the Hebrew University of Jerusalem, Israel, collected thousands of photos of people's faces. They labeled (贴标签于) each photo with four names. Then, they asked volunteers to guess which of the four names was correct.

    The volunteers were able to guess the right name 38% of the time. It seems that certain characteristics of faces give them clues about someone's name, Reader's Digest reported.

    However, this only worked when the volunteers looked at names from their own culture. In addition, the volunteers were not as good at guessing the real names of people who used nicknames(昵称)more often than their real names. This may show that a person's appearance is affected by their name only if they use it often.

    "This kind of face-name matching happens because of a process of self-fulfilling prophecy (预言), as we become what other people expect us to become," Ruth Mayo from tile university told science news website EurekAlert.

    Earlier studies have shown that gender (性别) and race stereotypes (刻板印象) can affect a person's appearance. The researchers believe there are also similar stereotypes about names. For example, people tend to think that men named Bob should have rounder faces because the word itself looks round. People may think that women named Rose are beautiful. They expect them to be "delicate" and "female", just like the flower they are named for.

    The "Give It Up for Earth Day" encourages people to commit to giving up actions that are harmful to the environment, such as using poisonous cleaners.

    Throughout the month of April, Canadians are being asked to "Give It Up for Earth Day!" Earth Day has been celebrated every year on April 22 since 1970. Earth Day Canada president Jed Goldberg says that as people become more environmentally aware, they want to find ways to reduce their environmental influence, not just celebrate one special event.

    "Earth Day is a great launching pad for thinking about environmental action every day," said Goldberg. "Choosing healthier options, even for the short term, can lead to thinking about the influence of our decisions for a lifetime."

    That's the reason behind the "Give It Up for Earth Day" campaign. It's designed to encourage healthy habits that benefit people and the planet. It challenges everyone to help create a healthier world by making changes in their daily routine.

    "We wanted to plan an action—targeted campaign that will give people a chance to act on their concern for the environment in a positive way," said Goldberg.

    The campaign has identified four daily actions that can add up to huge environmental savings. They include pledging (保证) to turn off the TV, give up the use of poisonous cleaners, reduce consumption of consumer products and cut out meat.

    At the end of April, all of the pledges will be recorded and converted (转化) into the number of TV hours not watched, dollars not spent on unnecessary items, electricity saved, greenhouse gas emissions (排放) avoided by cutting out meat, and poisonous chemicals produced from homes and landfills.

    "What we're trying to achieve this year for Earth Day is to give people a chance to do something that is meaningful and measurable," said Goldberg.